1. Field of the Invention
This present invention relates to a non-volatile semiconductor memory and a method for manufacturing the same.
2. Description of the Related Art
An electrically erasable programmable read-only memory (EEPROM) is known as a non-volatile semiconductor memory. In the EEPROM, a cell array is configured in such a way that a memory cell transistor is arranged at an intersection where a word line in the row direction and a bit line in the column direction cross over each other. Among EEPROMs, the NAND flash EEPROM in which a plurality of memory cell transistors are connected in series, and which can erase all the written data simultaneously, has been in wide use.
A memory cell transistor of the NAND type flash EEPROM includes n-type source and drain regions; and a p channel region between the source and drain regions. A stacked gate structure is formed on the channel region in which a control gate electrode and a floating gate electrode are stacked.
As the memory cell transistor has been minaturized, an interval between the source and drain regions of the memory cell transistor has become so narrow that influence of the short channel effect has increased in the NAND flash EEPROM.